public class Demo {
    static int count = 0;
    public static void main(String[] args) throws InterruptedException {
        Object locker = new Object();
        Thread t1 = new Thread(()->{
            synchronized (locker){
                for (int i = 0; i < 5000; i++) {
                    count++;
                }
            }

        });
        Thread t2 = new Thread(()->{
            synchronized (locker){
                for (int i = 0; i < 5000; i++) {
                    count++;
                }
            }

        });
        t1.start();
        t2.start();
        Thread.sleep(1000);
        System.out.println(count);
    }
}
